This invention relates to flanged corner constructions made from flexible materials and more particularly to corners for flexible hollow couplings, sometimes referred to as expansion joints.
Hollow flexible joints connect pipes, ducts and the like, and such joints are usually installed to allow limited movement of one part relative to another due to thermal expansion, vibration, misalignments and the like. Expansion joints are typically used to connect gas or air inlet or outlet ducts, such as are found in large drying, exhaust, heating, ventilating and power generating systems. These flexible joints may be quite large and may be made of a continuous length or belt of flexible material having a flange along each edge for connection to corresponding flanges of the ductwork.
If the openings to be connected are cylindrical, it is a relatively simple matter to provide a cylindrical segment of flexible material between the surfaces to be connected. In practice, however, many ducts are rectangular or square in cross section, and this requires that four flanged corners be formed or inserted into the structure of the joint.
Heretofore, the addition of flanged corner structures to expansion joints has been a time consuming and inefficient task. In accordance with the conventional procedure, the corners must be each separately fabricated from a number of pieces of curable material, and a separate curing operation is required. Each corner must then be spliced on each side to the straight portions of the expansion joint, or a total of eight splices for a four corner construction. The corner formation and splicing operations are time consuming and costly and increase the likelihood of imperfections, leaks and weaknesses in the joint.